Electrical device



Aug. 29, 1933. BARNETT 924,902

ELECTRICAL DEVICE Filed Jan. 11, 1929 & f2? R6 INVENTOR 224 o I25 Z 72 34 zab Patented: Aug. 29, 1933 PATENT; OFFICE UNITED STATES 4 Claims.

This invention relates to attachment fittings for electric circuits of the plug-in type for use in connection with lighting and power circuits, portable appliances, storage batteries, charging circuits, radio sets and other electric apparatus.

One object of the invention is to,provide an improved fitting of the character described which shall include in novel combination, current carrying parts having means for readily insert- 0 ing in series circuit therewith improved types of plug-in resistances orfuses. Where fuses are connected in circuit, they are incorporated so as to be more readily and safely inspected or replaced by even those unskilled in the electric arts.

Another object of this invention is to provide, for fittings of the character described and for other purposes, a plug-in resistance or fuse units of improved construction having projecting blades which readily permit each unit to be connected in and disconnected from circuit by simply inserting the blades into standard receptacle outlet sockets of the fitting for connecting in series circuit with current carrying engageable parts in said sockets. It is to be understood that the improved units embodying the invention are limited to exclude and distinguish from those constructions having screw plugs or Edison terminals.

A further object of the invention is to provide improved fittings and units of the character described comprising few and simple parts which shall form neat, rugged, compact. structures, which shall be cheap to manufacture, and practical and efiicient to a high degree in use.

Other objects of this invention will in part be obvious and in part hereinafter pointed out.

Certain features herein shown and described relate to subject matter contained in my Patent N0. 1,730,873, granted October 9th;1929 of which the present invention is a continuation in part.

The invention accordingly consists in the features of construction, combinations of elements and arrangement of parts'which will be exempli fied in the constructions hereinafter described and of'which the scope of application will be indicated in the following claims.

In the accompanying drawing, in which is shown various possible illustrative embodiments of this invention,

Fig. Us a front elevational view of an attachment fitting embodying the invention showing- 5 construction.

fitting corresponding to a section taken on lines 69 3-3 in Fig. 1.

Fig. 4 is a bottom plan view of a fuse unit embodying the invention, showing the cover portion removed.

Fig. 5 is a view corresponding to a section taken on lines 5--5 in Fig. 4 with the cover portion in place.

Fig. 6 shows perspective views of the current carrying parts removed from the fitting. I

Fig. 7 is a front elevational view of an im- 79 proved unit partly in section showing the interior construction of an improved resistance unit; and

Fig. 8 is a fragmentary view, partly in section, showing an application of the invention to a screw shell or Edison type fuse receptacle.

Referring in detail to the drawing, 10 denotes an attachment fitting embodying the invention adapted to connect with a suitable power source outlet (not shown) or interposed into circuit between the two conventional parts of a separable attachment device such as plug 11 and cap 12 of any standard construction in the well understood manner. As shown in Fig. 1, the fitting 10 has its opposite ends 10a and 10b engaged with the plug 11 and the cap 12, respectively.

The fitting 10 may comprise a body of two identical mating halves 13 which are preferably molded of insulating materials, such as porcelain, pheno-condensate compounds or other suitable substances. The halves 13 have fiat interior surfaces 13a, which when said fitting. is assembled, are in abutment and preferably releasably retain between them current carrying portions 14. A clamping screw 25 extending through aligned passages 13b in the halves 13 may be provided for holding said halves and portions assembled to form a rigid unitary structure.

The current carrying portions 14 may comprise two pairs of identical members, each pair consisting of a contacting jumper .5 having spring terminal ends 15a and 15b and a blade member 16, having a prong terminal 16a at one end and a spring terminal 16b at the other end.

The halves are each formed with an extension 130 in the side opposite the surface 13a. Each' extension 130 has a pair of parallelly aligned spaced passages 13d and 13e extending there-' through forming sockets into which a terminal 16b and a terminal end 15a are fitted. The surgrooves 13} and 13g which are adapted to register for receiving spring terminal end 1511 of the jumpers 15 and prong portions 16b of the blade member 16, respectively. Free end portions of the prong terminals 1611 project outwardly from the plug end 10a of the fitting 10. The grooves 13 are extended through the receptacle end 10b to form slot openings at 13h. These grooves and the passages 13d and 13e are each made sufllciently wide to permit insertion through .the openings 13h and into said passages 13d and 13a, the terminal blades 11a of the cap 12 or similar prong plug connectibles of other circuit portions for contacting with the spring terminals 15a,'15b and 16b.

The fitting 16 when assembled with the contacting jumpers 15 and spring terminal member 16 in position between the halves 13 of the body are positively separated and braced because of their confined position in the passages and grooves. Thus it is clear from the above description and the drawing, that fitting 10 comprises few, simple, duplicate parts which are readily assembled to form a neat, compact, rugged unitary structure.

In using the invention, the assembled'fltting may be connected in circuit as shown in Fig. 1. To guard the circuit to which the fitting is applied from being overloaded and to protect an appliance (not shown) connected in circuit through the cap 12 that is, limiting the maximum current flow passing fromthe attachment plug 11 through the fitting 10 to the portable conductor wire 1'7, connected to said cap 12, improved units 20, each having incorporated therewith a fusible element 21 as shown in Figs. 4 and 5, or a resistance 22 as shown in Fig. 7 are used to complete the circuit through the current carrying paws 14.

The units 20 may be constructed like any conventional type of cap 12 with the exceptions as will hereinafter be noted. As seen from Figs. 4 and 5, each unit 20 comprises a body 23 formed of a suitable insulating material having spaced terminal blade members 24 secured in any suitable nianner as by means of metallic eyelet anchors 28 to extend from a side of said body 23. Said side may be fitted with a cover portion or plate 26 made of insulating sheet material to form a bottom closure for the unit. The free prong ends 24a of the blade members 24 project through the 'plate 26 and the other ends of said members are formed with flat extensions 24?) which are firmly secured to the body portion 23 by the overturned ends of said eyelet anchors 28.

f A binding screw 29 is provided on each extension 24a for securing an end of the fusible link element 21 so that the latter electrically bridges the blade members 24. The body 23 has a passage compartment 23a extending centrally therethrough between the blade members 24 from the cover plate 26 to a top opening 23b. The rim of the latter is preferably made to be fitted with a transparent window 30 of incombustible sheet material such as mica which serves to enclose the element 21 within the passage compartment 23a.

As seen from Fig. 5, the condition of the element 21 may readily be determined by inspection through the window 30.

It should be noted the spaced through passages 13d and 13e in the fitting extensions 130 are positioned with their greatest widths of the passage openings of each extending parallel to the fitting ends 10a and 10b, thereby requiring a minimum material in forming the current carrying parts 14 and separating said parts to provide an open circuit between the pairs of terminal ends 162) and 15a. in the passages 13d and 13e, respectively. By inserting the prong ends 24a of the unitsw20 into the passages 13d and 13a to contact with the terminals 16b and 15a, the circuit through the current carrying parts 14 is completed through the fuse element 21 bridging the blade members 24.

The units may be removed for inspection or replaced merely by applying a pulling or pushing force to the body 23, and when said units are dismounted, not only is the circuit opened, but the live current carrying parts are shielded against accidental contact, so that the fitting may be handled with safety by women or children or other unskilled persons. This safety feature is obviously not possible with the conventional types of fusing devices such, for, example, as with the standard screw plug fuse.

The improved form of circuit fusing means comprising the fittings 10 or its equivalent and the units 21' not only are relatively cheap devices but also facilitate the ready replacement of fuse elements. This permits testing of the circuit with greatest freedom from liability of being shocked in contacting live circuit parts even when done carelessly, being practically fool proof. w

The simplicity of construction of the current carrying parts are clearly shown in Fig. 6. Here the contact jumper 15 is seen to comprise a strip of spring metal having the opposite end terminals 15a and 15b extending in angular relation with respect to each other, said terminals presenting folds 15c and 15d which extend in right angle relations to each other to serve as receiving spring ends.

The blade members 16 are each made of rigid strips which form the prong terminal at one end 16a and have the spring metal ends 16b secured to the strip at the other end in any suitable manner as by riveting or soldering.

In Fig. 7 a modified construction of current limiting unit 120 is shown. Here the fusible element is replaced by the resistance element 22. The latter may be of any suitable construction as, for example, may be mounted on a spool 122 which has one end 122a supported by the body 125 123 so that the ends 22a of the resistance element 22 can be readily connected to the binding screws 129. The units 120 are connected in circuit through the blade members 126 in the same manner as described above for the units 20. While the latter serve to limit the maximum current that may pass through the improved fitting the units 120 limit the current flowing to a fixed amount in the well understood manner.

Another important adaptation of the invention is shown in Fig. 8. Here a standard screw shell or Edison receptacle 210 is connected in one line of a circuit for receiving a standard fused unit in series therewith. Into said receptacle 210, a standard plug 11 is screwed. Now by inserting one of the units 20 into said plug 11, a fuse link 21 is connected in series circuit without the necessity of screwing the plug 11 from the' receptacle 210 which may be removed or replaced by simply dismounting the unit 20 without exposing the live parts of the receptacle.

As various possible embodiments might be made of the above invention, and as various changes might be made in the embodiment above set forth, it is to be understood that all matter herein set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. An electric unit of the character described comprising a plug cap formed of an insulating body having a central passage extending therethrough, a transverse annular shoulder adjacent one end thereof, spaced parallelly aligned terminal contact blades secured to said body and extending freely and outwardly from one end 01' the passage, said contact blades having lateral extensions lodged on said shoulder, means ior anchoring said extensions on said shoulder, a binding post carried by each of said extensions, a current limiting member disposed in said passage secured to said binding posts to electrically interconnect said blades, a closure for said passage at one end thereof, and a readily removable closurefor said passage at the other end, whereby the" current limiting member may be readily replaced, thereby permitting the facile replacement of said current limiting member.

2. A device adapted to be interposed between the two conventional parts of a separable attachment plug comprising an insulating body having a pair of parallelly spaced flat sides, one of said sides having socket recesses extending perpendicularly into the body, spring terminals within said recesses adapted to receive the blades of a cap,

body, and spring terminals within the 1m mentioned recesses forming an open circuit between.

each of the first mentioned spring terminals and one or said contact blades, said last mentioned recesses adapted to receive the prongs of a current limiting unit for bridging the open circuited spring terminals.

3. In a device of the character described, an insulating body portion, current carrying parts including a blade member and a contact jumper retained in said body portion, said blade member being terminated at one end by a prong extending beyond said body portion and a spring terminal at the other end of said member opposite said prong, said jumper having spring terminal ends, one of the last mentioned terminal ends being positioned in spaced alignment with respect to the spring terminal of said blade member to provide an open circuit adapted to receive prongs of a current limiting unit for bridging the said open circuit.

4. In an attachment plug oi the character described, a current carrying part comprising a blade member and a contact Jumper, said blade member having a prong terminal at one end and a spring terminal extending substantially at right angles with respect to said prong terminal at the other end, said jumper having spring terminal ends extending in substantially right angle relation with respect to each other, said prong terminal being aligned with one of the spring terminal ends of said jumper, the other spring'terminal end of said jumper being spaced and aligned with respect to the spring terminal or said blade member.

LOUIS BQRNE'I'I. 

